Viability Selection of Bovine Oocyte Using Annexin-V Assay

Morphological characteristic is the primary reference for selecting viable cumulus-oocyte-complex (COCs). Annexin-V assay has been suggested for isolating these viable cells based on apoptosis status. This study compared fertilization rate between Annexin-V selected COCs with morphologically healthy selected COCs. Minimal binding time between Annexin-V and the COCs was determined to ensure slight disruption. Before observation with florescent microscope, eighty-two cattle’s COCs were incubated with the Annexin-V assay for 5 min, 15 min and 24 hours. Further, 157 COCs were separated into 2 groups; positively (n=76) and negatively (n=81) tagged with annexin-V-FITC and PI fluorescent signals. Once separated, control comprised of non-stained COC (n=68) and the two afore mentioned groups were matured, fertilized and cultured (IVM-IVF-IVC). After 72 hpi, cleavage rate was determined. Results shows the binding between annexin-V assay and the nonviable COC had occurred as early as 5 min with positively and negatively tagged COCs were 44 (53.7%) and 38 (46.3%) respectively. The fertilization rate of control group (66%), negatively tagged (79%) and positively (50%) tagged COCs was significantly different (?² (2) = 14.60, p < 0.05) between the groups. In conclusion, oocyte selection using annexin-V-FITC had significant differences in cleavage rate compared with oocytes assumptive as morphologically healthy. Based on COCs Annexin-V assay, COC that are assumed as morphologically healthy is a mixture of viable and nonviable oocytes.